Stiffening of portions of shoe uppers by coating the portion to be stiffened with a layer of molten resin and solidifying the resin was disclosed in the U.S. patent to Chaplick et al. U.S. Pat. No. 3,316,573. In that patent, molten thermoplastic polymeric material was spread as a layer on a shoe upper at a temperature at which the thermoplastic material has a viscosity low enough to wet and adhere to the surface of the article to be stiffened but sufficiently high so that it will substantially not penetrate the shoe component. The layer of material so formed was cooled and shaped to form a stiff resilient layer holding the article in the desired configuration.
The U.S. patent to Hollick U.S. Pat. No. 4,127,910 discloses the stiffening of a selected area of sheet material such as a shoe upper through the use of a procedure of forming a layer of resin from a hot molten source which is particularly adapted for use in stiffening of heel end portions of the shoe upper. According to that patent, a molten resin is spread over an area of flexible sheet material to be stiffened by heat-pressing in which the sheet material is molded to a desired three dimensional shape and is then secured in lasted relation to an insole in a molding step in which the initial pressing and ultimate molding step are carried out while the resin is in a heat moldable state.